The present invention relates generally to methods and apparatus for cooling patients for therapeutic purposes, and more particularly to systems for establishing central venous access while providing a means for cooling a patient.
It has been discovered that the medical outcome for a patient suffering from severe brain trauma or from ischemia caused by stroke or heart attack is degraded if the patient""s body temperature rises above normal (38xc2x0 C.). It is further believed that the medical outcome for many such patients might be significantly improved if the patients were to be cooled relatively quickly for a short period, e.g., 24-72 hours. Apart from the therapeutic benefits of hypothermia, the outcomes for brain trauma or ischemia patients that develop fevers is worse than for patients that do not develop fevers. Consequently, temperature management for such patients is important, even when hypothermia is not to be used to treat the patients. Moreover, prophylactic short-term hypothermia might help patients undergoing minimally invasive heart surgery and aneurysm surgery.
The affected organ, in any case, is the brain. Accordingly, systems and methods have been disclosed that propose cooling blood flowing to the brain through the carotid artery. An example of such systems and methods is disclosed in co-pending U.S. pat. app. Ser. No. 09/063,984, filed Apr. 21, 1998, owned by the present assignee and incorporated herein by reference. In the referenced application, various catheters are disclosed which can be advanced into a patient""s carotid artery and through which coolant can be pumped in a closed circuit, to remove heat from the blood in the carotid artery and thereby cool the brain. The referenced devices have the advantage over other methods of cooling (e.g., wrapping patients in cold blankets) of being controllable, relatively easy to use, and of being capable of rapidly cooling and maintaining blood temperature at a desired set point.
As recognized in co-pending U.S. pat. app. Ser. No. 09/133,813, filed Aug. 13, 1998, owned by the present assignee and incorporated herein by reference, the above-mentioned advantages in treating brain trauma/ischemic patients by cooling can also be realized by cooling the patient""s entire body, i.e., by inducing systemic hypothermia. The advantage of systemic hypothermia is that, as recognized by the present assignee, to induce systemic hypothermia a cooling catheter or other cooling device need not be advanced into the blood supply of the brain, but rather can be easily and quickly placed into the relatively large vena cava of the central venous system.
Moreover, since many patients already are intubated with central venous catheters for other clinically approved purposes anyway, providing a central venous catheter that can also cool the blood, if only to manage temperature and thereby ameliorate fever spikes, requires no additional surgical procedures for those patients. A cooling central venous catheter is disclosed in the present assignee""s co-pending U.S. patent application Ser. No. 09/253,109, filed Feb. 19, 1999 and incorporated herein by reference. The present inventions are directed to central venous cooling devices.
An introducer sheath for a central venous line catheter includes a hollow body defining a proximal end, a distal end positionable in a patient, and at least one catheter placement lumen extending therebetween. A barrier such as a septum or hemostasis valve is in the lumen at or near the proximal end of the body for selectively blocking the lumen, and at least one temperature sensor such as a thermistor or thermocouple is mounted on the body at or near the distal end for generating a temperature signal. The catheter can include at least one distally-located cooling membrane.
If desired, the body of the sheath further includes a coolant supply lumen and a coolant return lumen. Both the coolant supply lumen and coolant return lumen communicate with a distally-located heat transfer region associated with the body. The heat transfer region can be established by at least one membrane that is attached to the body, or by at least one distally-located fluid passageway that is formed in the body.
In another aspect, an introducer sheath for a central venous line catheter includes a hollow body defining a proximal end, a distal end positionable in a patient, and at least one catheter placement lumen extending therebetween. The body also defines a coolant supply lumen and a coolant return lumen. A barrier is disposed in the catheter placement lumen at or near the proximal end of the body for selectively blocking the catheter placement lumen, and a distally-located heat transfer region is associated with the body in communication with the coolant supply and return lumens.
In yet another aspect, a jugular vein catheter system includes a catheter body bearing at least one oxygen sensor connected to an optical fiber. An oxygen measuring system is connected to the fiber, and a heat exchange region is associated with a distal segment of the catheter body.
In still another aspect, an arterial catheter system includes a catheter body bearing at least one blood lumen, and a dialysis system communicating with the blood lumen. A heat exchange region is associated with a distal segment of the catheter body.
In another aspect, a heat exchange catheter includes a catheter body defining at least a coolant supply lumen, a coolant return lumen, and an air lumen. A cooling membrane defines a chamber that communicates with the coolant supply and return lumens, and an inflation balloon is disposed in the chamber. The inflation balloon is selectively movable between an inflated configuration, wherein the inflation balloon causes coolant to flow near an outer surface of the cooling membrane to thereby effect relatively greater heat exchange with the blood, and a deflated configuration, wherein coolant tends to flow through the cooling membrane with a laminar flow characteristic nearer the catheter body than the outer surface of the cooling membrane.
In still another aspect, a central venous access system includes a multi-lumen catheter, at least one heat exchange membrane or balloon located distally on the catheter and communicating with at least one coolant lumen of the catheter, and a heat exchange system communicating with at least the coolant lumen. Coolant is circulated between the heat exchange system and the membrane or balloon to effect heat exchange with a patient. At least one holder is engageable with the catheter to hold the catheter onto a patient. Also, a central venous system communicates with at least one lumen of the catheter.
The present invention also discloses an improvement to a Foley catheter configured for placement in the urinary tract of a patient. The improvement includes at least one heat exchange membrane or balloon located distally on the catheter body and communicating with at least one coolant lumen of the catheter. A heat exchange system communicates with at least the coolant lumen, with coolant being circulated between the heat exchange system and the membrane or balloon to effect heat exchange with a patient.
Moreover, a method is disclosed for heat exchange with a patient. The method includes advancing a catheter into the urinary tract of a patient, and circulating saline through the catheter in a closed loop to exchange heat with the patient.